Known systems from the prior art for the generation of images, also known as “Picture Generating Units” (PGUs) or Image Generating Units” (IGUs), are constructed with light emitting diodes with increasing power and luminous intensity and special lenses, in particular collimator lenses. The construction of the systems for image generation with high-performance light emitting diodes, also called high-performance LEDs, serves to increase the intensity of the display illumination and therefore the brightness of a generated virtual image.
The use of high-performance LEDs can cause a rise in the emission of heat inside the systems, in particular in the area in front of the light-emitting element, that is, especially in the area between the light-emitting element, the collimator lens, and a display device. Due to the increasing emission of heat, the temperature rises in the area in front of the light-emitting element in such a manner that the admissible limit of the working temperature of the display device is exceeded. The display device can fail or be destroyed. The area is also designated as a high-temperature area.
Traditional systems for image generation comprise a heat sink constructed as a cooling body. However, a cooling body thermally coupled to the light-emitting element cannot completely remove the heat emitted from high-performance LEDs, so that the temperature inside the high-temperature area between the collimator lens and the display device sharply rises.
The systems for image generation are also used as components of display devices such as a so-called “head-up-display” and are arranged, for example, in the area of the windshield of a motor vehicle. The term head-up-display, also abbreviated as HUD, denotes a display system in this context with which the user can retain the position of his head and/or the direction of view in the original alignment when observing the displayed information since the information is projected into his field of view. HUDs generally comprise an image-forming unit which generates an image, a lens module and a projection surface. The lens module guides the image onto the projection surface, which is constructed as a reflecting, transparent plate. The vehicle driver sees the reflected information of the image-forming unit and at the same time the actual environment behind the disk.
US 2007/0064174 A1 teaches a device with a light unit and a display unit, in particular a HUD. The light unit comprises illumination elements arranged between a reflector and a heat-blocking layer, through which a liquid crystal panel is illuminated.
EP 1 865 534 B1 discloses a light emission device with a light emission panel and a diffuser plate for diffusing the light emitted by the light emission panel. The device comprises a heat dissipation plate arranged between the light emission panel and the diffuser plate and which is constructed from a material with high thermal conductivity.
Moreover, in addition to the heat blocking layer and heat dissipation plate, ventilators, cooling coils and heat-absorbing filters are used in the prior art.
The systems known from the prior art comprise a plurality of components that are arranged inside the beam of the light emitted by the light-emitting elements and which reduce the intensity of the light exiting from the device. The components provided in the prior art devices can just adequately dissipate the emitted heat. Furthermore, the light emission devices have no connection to a display device which is to be protected from overheating.
There exists a need for a device for the emission of light, in particular to generate an image, in which the heat emitted by light-emitting elements, for example, high-performance LEDs, is more effectively dissipated from a high-temperature area in order to avoid destruction of or damage to the device. Elements for dissipating the heat are to be constructed in combination with a device for generating an image in such a manner that limit temperatures of individual components are not achieved or exceeded. The number of components of the device for the emission of light should be minimal in order to minimize the manufacturing costs. On the other hand the components for removing the heat should be constructed so that the light intensity is not additionally influenced or reduced.